Method for eliminating static electricity



Jan 29, 1963 J. VlSICARDl METHOD FOR ELIMINA'MING STATIC ELECTRICITY Filed May 19, 1954 CAKE OF DRY ICE DRY ICE HOLDER PRINTING PLATE- CYLINDER 70 GAS COLOR RESERVOIR CHUNKS OF DRY ICE WATER WIND-UP ROLLER DOCTOR BLADE TEXTILE TO BE TREATED IMPRESSION CYLINDER INVENTOR JOHN VISCARDI.

HIS ATTORNEYS.

United Stats Filed May 19,1954, SEE. No. 430,911 7 Claims. (Cl. 317-4 This invention relates to novel methods and apparatus for eliminating the occurrence of static electricity from various material processing operations.

As is well known in the art, when two dissimilar materials are rubbed or pressed together and then separated, equal and opposite charges are produced on the two materials, the amount and sign of the charges being dependent on the nature of the contacting surfaces, in accordance with the laws of triboelectricity. This phenomenon has given rise to many serious difiiculties in various processing operations, particularly where a material being operated upon slides relative to or moves into and out of contact with the processing machinery, such as in phonograph record making and various textile processing operations. The resultant charges of static electricity on the machinery and material frequently reach proportions endangering the operating personnel and adjacent structures. While various means have been employed in the past in an attempt to overcome the problems of static electricity, these have not proved satisfactory, being completely without elfect in many operations and only partially effective in others, even at substantially reduced operating speeds.

It is one object of the present invention to provide simple and efficient means which overcomes the above mentioned difiiculties, and which substantially completely eliminates static electricity from various operations in which rapidly moving machinery contacts the material being processed thereby. While the method and apparatus of the present invention have been primarily developed and employed in connection with textile printing procedures, and will be fully described hereinafter with particular reference thereto, the invention has been found entirely satisfactory in a wide variety of other operations, including the molding, stamping and manufacture of phonograph records and other plastic articles.

It is another object of the present invention to provide a highly improved method of textile printing in which the occurrence of static electricity is substantially completely eliminated, so as to remove the heretofore inherent danger of electric shock and fire. Further, the method Of the present invention serves to permit considerably greater textile printing speeds, while also enhancing the quality and increasing the vividness of the printed material.

It is still another object of the present invention to provide a method and apparatus of the type described which are simple and reliable in operation and construction, and which effect considerable savings in processing and handling time to substantially reduce the cost of the finished product.

It is a more particular object of the present invention to provide a method of eliminating static electricity from material and article processing and molding operations by the application of carbon dioxide to the material or article being processed or molded, which method includes all the advantageous characteristics mentioned above, and produces an improved end product from which the carbon dioxide will completely remove itself, or may readily be removed without affecting the processed material.

Other objects of the present invention will become apparent upon reading the following specification and referice , ring to the accompanying drawings, which form a material part of this disclosure.

The invention accordingly consists in the features of construction, and combinations and arrangements of elements and method steps, which will be exemplified in the following description, and of which the scope will be indicated by the appended claims.

The single FIGURE of the drawing schematically represents a side elevational view of textile printing apparatus constructed in accordance with the present invention.

Referring now more particularly to the drawing, the embodiment of the invention illustrated therein comprises a printing mechanism, generally designated 10, a web of textile material, generally designated 11, which passes through the printing mechanism and is wound upon the wind-up roller 12.

The printing mechanism 10 includes the usual metal printing plate cylinder 14 arranged above and in engagement with the upper surface of the textile web 11, and is rotatable in a counter clockwise direction as indicated by the arrow. A dye or color reservoir v15 including a doctor blade 16 is disposed adjacent to and opening toward the printing plate cylinder for applying coloring matter thereto. Directly below the printing plate cylinder 14- and in supporting engagement with the underside of the textile web 11 during the printing thereof is an impression cylinder 17. The impression cylinder is rotatable in a clockwise direction, and combines with the printing plate cylinder to efliect movement of the textile web from left to right.

The textile web passes toward the right over a supporting roller 19, as at 2%, in the direction of the arrow and passes thence leftward and downward under the guide roller to the upper side of the wind-up roll. The latter rotates in a counter clockwise direction and thereby effects spiral winding of the Web of textile material. The apparatus, and operation thereof, as thus far described, are conventional so that a more detailed description is not necessary.

In accordance with the present invention, carbon dioxide is applied to a material being processed, whether it be textiles during printing thereof or other materials involving diiferent operations. Toward this end, a holder 22, which holds a block 24 of solid carbon dioxide or Dry Ice is fixedly positioned by any suitable means (not shown) adjacent to and above the printing plate cylinder 14. The holder 22 has its upper end open as at 23 for receiving said block of solid carbon dioxide 24. The lower end 25 of the Dry Ice holder is also open and faces to ward the printing plate cylinder to permit extension of the mass or block 2-4 of Dry Ice downwardly therethrough and into engagement with the printing plate cylinder. That is, the Dry Ice block 24 is supported in position above the printing plate cylinder by the holder 22 and permitted to engage with and rest on the printing plate cylinder. At normal room temperature Dry Ice sublimes to form gaseous carbon dioxide, also called carbonic acid gas. Obviously, frictional engagement of the printing plate cylinder with the Dry Ice will serve to accelerate sublimation. The evolved sublimate of gaseous carbon dioxide flows downwardly along the periphery of the printing plate cylinder to contact with the textile web 11. Thus, the current of carbonic acid gas is applied to the material being processed, both from the surrounding or ambient atmosphere, and from an element of the processing machinery. While this construction and arrangement for applying carbonic acid gas to the material being processed has been found extremely simple and efficient, and serves to substantially completely eliminate static electricity from both the equipment and material, it is appreciated that other means for applying the CO gas may be found to be satisfactory or more desirable under the particular circumstances. I thus disclose the use of freshly .gasified anti-static carbon dioxide, which is taken from a source which consists of carbon dioxide in the non-gaseous state. As is Wellknown, solid carbon dioxide has a low temperature of approximately minus 140" Fahrenheit. It is also well-known that the evolved gaseous carbon dioxide has a temperature of minus 110 Fahrenheit and that one volume of commercial solid carbon dioxide will evolve approximately 500 volumes of gas. I do not claim the non-gaseous source of carbon dioxide per se. Tests have shown that when carbon dioxide is directly freshly gasified from a source of carbon dioxide in the non-gaseous form of said gas, such fre'shly-gasified carbon dioxide has an inherent electric charge. Such inherently charged, freshly-gasified carbon dioxide is conveniently designated as anti-static, because it discharges static electricity from webs of textile materials, plastics, etc.

As an optional or additional means for applying carbonic acid gas to the material being operated upon, there is provided an open top receptacle 27 fixedly positioned adjacent to and below the textile web 11. Contained within the receptacle or pan 27 is a quantity of Warm water, or other suitable heating liquid, and one or more chunks or masses of Dry Ice which are rapidly sublimed under the moderate heat of the warm water. The evolved current of gaseous carbon dioxide will rise into contact with the passing web for application thereto. The invention herein is not to be limited to any specific form or design of receptacle or pan, as it is obvious that any desired or convenient type of receptacle or pan may be employed.

While the physical and chemical actions involved herein are not completely understood, the contact of substantially unheated carbonic acid gas with textile, plastic and other materials being processed or manufactured by rapid ly moving machinery, has been found to substantially completely eliminate the occurrence of electric charges in both the machinery and material and article being processed thereby. As is well known, many textile materials, such as nylon, are made of a material which is classified as a plastic, and the invention is particularly useful in preventing the accumulation of static electricity on a textile fiber or web which is made of a plastic. Obviously, operating speeds for such processes may be considerably increased, and subsequent handling of the processed materials and articles will be facilitated by the absence of electric charges thereon. In the case of printing on textiles, the method of the present invention has also been found to produce more vivid and attractive printed material. While the invention herein has been described by way of example with respect to a single color printing press, it is equally applicable to a multi-color printing press.

From the foregoing, it is seen that the present invention fully accomplishes its intended objects, and provides a method and apparatus for eliminating static electricity in material processing operations which is well adapted to meet practical manufacturing conditions.

Industrially, static is often mistaken for frictional heat. It has been found that carbon dioxide applied to a source of frictional heat eliminates or considerably reduces such heat. It has been also found that unheated carbon dioxide will eliminate static electricity.

Although the present invention has been described in some detail by way of illustration and example for purposes of clarity of understanding, it is understood that certain changes and modifications may be made within the spirit of the invention and scope of the appended claims.

What is claimed is:

l. A method of eliminating static electricity which is evolved by friction in processing machinery and material processed therein, which consists in applying freshly-gasitied and anti-static carbon dioxide to said material during the processing thereof by directly evolving said freshlygasified carbon dioxide from carbon dioxide in the nongaseous state form of said gas, said freshly-gasified carbon dioxide being applied in suflicient concentration for said purpose at a temperature below the temperature which is required to substantially ionize gaseous carbon dioxide by heat.

2. A method according to claim 1, in which said freshly-gasified carbon dioxide is applied directly to an element of said machinery which contacts said material, and said freshly-gasified carbon dioxide is transferred by said element to said material.

3. A method according to claim 1, in which the freshlygasified carbon dioxide is produced by subliming solid carbon dioxide, and said freshly-gasified carbon dioxide is applied without substantially heating the same.

4. A method of substantially removing static electricity from an object which is located in an atmosphere of air and on whose surface static electricity is generated by friction, which consists in directly freshly gasifying carbon dioxide in the antistatic state from a non-gaseous form of carbon dioxide, introducing a current of said freshly-gasilied and anti-static carbon dioxide into said atmosphere of air, and directing said current of anti-static and freshlygasified carbon dioxide upon said object to provide a mixed atmosphere or" air and anti-static freshly-gasified carbon dioxide at said object, said mixed atmosphere having a suflicient concentration of said freshly-gasified and anti-static carbon dioxide to discharge the static electricity from said object, said mixed atmosphere having a temperature below the temperature at which said mixed atmosphere is substantially ionized by heat.

5. A method according to claim 4, in which said object is a moving web.

6. A method according to claim 4, in which the temperature of said current of anti-static, freshly-gasified carbon dioxide is below the temperature of said atmosphere of air.

7. A method according to claim 4, in which said object is a plastic.

References Cited in the file of this patent UNITED STATES PATENTS 740,233 Clark Sept. 29, 1903 937,759 Blake Oct. 26, 1909 1,338,071 Cohen Apr. 27, 1920 1,394,064 Chapman Oct. 1 8, 1921 1,472,450 Yetter 'Oct. 30, 1923 r 1,749,316 Catlin Mar. 4, 1930 1,836,536 Lance Dec. 15, 1931 2,086,000 Roren July 6, 1937 2,147,651 Jones Feb. 21, 1939 2,194,775 Stadtfeld Mar. 26, 1940 2,242,399 Kurth May 20, 1941 FOREIGN PATENTS 478,263 Great Britain Jan. 17, 1938 

1. A METHOD OF ELIMINATING STATIC ELECTRICALLY WHICH IS EVOLVED BY FRICTION IN PROCESSING MACHINERY AND MATERIAL PROCESSED THEREIN, WHICH CONSISTS IN APPLYING FRESHLY-GASIFIED AND ANTI-STATIC CARBON DIOXIDE TO SAID MATERIAL DURING THE PROCESSING THEREOF BY DIRECTLY EVOLVING SAID FRESHLYGASIFIED CARBON DIOXIDE FROM CARBON DIOXIDE IN THE NONGASEOUS STATE FORM OF SAID GAS, SAID FRESHLY-GASIFIED CARBON DIOXIDE BEING APPLIED IN SUFFICIENT CONCENTRATION FOR SAID PURPOSE AT A TEMPERATURE BELOW THE TEMPERATURE WHICH IS REQUIRED TO SUBSTANTIALLY INOZIE GASEOUS CARBON DIOXIDE BY HEAT. 